1. Technical Field
The present invention relates to a liquid crystal device that irradiates illumination light from the rear side of a liquid crystal panel, and an electronic apparatus.
2. Related Art
In general, a liquid crystal device used as a display unit of an electronic apparatus includes a liquid crystal panel and a backlight which is disposed at the rear side of the liquid panel as an illumination element. In order to reduce power consumption, a portable electronic apparatus such as a mobile phone uses a semi-transmissive reflective liquid crystal device that includes a transmissive display mode in which displaying is performed by transmitting illumination light of the backlight, and a reflective display mode in which displaying is performed by reflecting ambient light that exists outside a mobile phone casing.
The backlight of the liquid crystal device may be an LED (Light Emitting Diode). A control circuit that controls illumination light intensity by regulating current supplied to the LED is installed in the liquid crystal device. In order for the liquid crystal panel to perform displaying with good quality according to external brightness of the electronic apparatus, an liquid crystal device has been proposed in which an optical sensor that measures ambient light intensity is installed, so that the control circuit regulates backlight intensity based on the measurement result obtained by using the optical sensor (see JP-A-2005-121997).
It is desirable that a detection position of the ambient light to be detected by the optical sensor is located near a display area of the liquid crystal panel. Thus, the optical sensor may be installed inside the liquid crystal panel.
In the past, the liquid crystal device had some problems as follows. That is, polarizing plates are respectively disposed in the front side and the rear side of the display area of the liquid crystal panel. In general, since un-polarized ambient light is transmitted through the polarizing plate disposed in the front side, ambient light intensity reduces by approximately half. For this reason, intensity of light received into a light receiving surface of the optical sensor is significantly decreased by the polarizing plate, and thus the ambient light cannot be sufficiently received at the light receiving surface. Accordingly, in order for the ambient light detected by the optical sensor to have good sensitivity, the light receiving area of the optical sensor disadvantageously needs to be large. Further, since the light receiving area is large, the display area of the liquid crystal device has to be narrowed, and exterior design of the liquid crystal device deteriorates.